Methods, systems, and computer readable media for evolved general packet radio service (GPRS) tunneling protocol (eGTP) indirect tunneling in a voice over LTE (VoLTE) simulation

ABSTRACT

Methods, systems, and computer readable media for initiating evolved general packet radio service (GPRS) tunneling protocol (eGTP) indirect tunneling are disclosed. According to one method, the method occurs at a long term evolution (LTE) node simulator including a module for processing data packets. The method includes receiving a data packet associated with a user device. The data packet includes an endpoint identifier for identifying a first transceiver simulated by the LTE node simulator. The method also includes determining, using the endpoint identifier, whether the data packet should be processed by the module. The method further includes in response to determining that the data packet should be processed by the module, processing the data packet. The method also includes in response to determining that the data packet should not be processed by the module, initiating routing the data packet to a network node.

TECHNICAL FIELD

The subject matter described herein relates to mobile network equipmenttesting. More specifically, the subject matter relates to methods,systems, and computer readable media for initiating eGTP indirecttunneling.

BACKGROUND

In some mobile networks, user devices (e.g., smartphones, computers,mobile handsets, or other user equipment (UE)) may be connected to acore network and/or the Internet via a radio access network (RAN). Eachmobile network may include transceivers, such as base stations, node Bs,or evolved node Bs (eNBs), for facilitating communications between userdevices, networks, and/or nodes (e.g., web and media servers). In avoice over long term evolution (VoLTE) environment, an eGTP protocol maybe used to transport Internet protocol (IP) packets from external packetnetworks to user devices.

While an eGTP protocol may be used to transport IP packets betweenvarious portions of an LTE or an evolved packet core (EPC) network,problems can arise during mobility events. To ensure that no packets arelost during mobility events and to increase end to end reliability, sometraffic may be sent back to a core network for transmission to anotherdestination. For example, traffic originating in the Internet may berouted through the core network towards a user device. When the userdevice detaches from a first eNB and moves to a second eNB, the packetsthat are already on the way towards the first eNB may need to be routedthrough indirect tunnels (e.g., via various nodes in the core network)to the second eNB.

While routing packets to the core network may prevent packets from beinglost in conventional LTE networks, mobile network equipment simulationand/or testing platforms add further complexity. For example, a LTE nodesimulator may simulate multiple eNBs and user devices. Each simulatedeNB may be responsible for transferring data between multiple userdevices and for handling numerous mobility events. As a result, thesimulator must simulate mobility events for multiple user devices andhandle multiple instances of indirect tunneling. Thus, mobile networkequipment simulation and/or testing platforms may require initiatingindirect tunneling in an efficient and highly scalable manner.

Accordingly, in light of these difficulties, a need exists for improvedmethods, systems, and computer readable media for initiating eGTPindirect tunneling.

SUMMARY

Methods, systems, and computer readable media for initiating evolvedgeneral packet radio service (GPRS) tunneling protocol (eGTP) indirecttunneling are disclosed. According to one method, the method occurs at along term evolution (LTE) node simulator including a module forprocessing data packets. The method includes receiving a data packetassociated with a user device. The data packet includes an endpointidentifier for identifying a first transceiver simulated by the LTE nodesimulator. The method also includes determining, using the endpointidentifier, whether the data packet should be processed by the module.The method further includes in response to determining that the datapacket should be processed by the module, processing the data packet.The method also includes in response to determining that the data packetshould not be processed by the module, initiating routing the datapacket to a network node.

A system for initiating eGTP indirect tunneling is also disclosed. Thesystem includes a long term evolution (LTE) node simulator including amodule for processing data packets. The module is configured to receivea data packet that includes an endpoint identifier for identifying afirst transceiver simulated by the LTE node simulator, to determinewhether the data packet should be processed by the module, in responseto determining that the packet should be processed by the module, toprocess the data packet, and in response to determining that the packetshould not be processed by the module, to initiate routing the datapacket to a network node.

The subject matter described herein may be implemented in software incombination with hardware and/or firmware. For example, the subjectmatter described herein may be implemented in software executed by aprocessor (e.g., a hardware-based processor). In one exemplaryimplementation, the subject matter described herein may be implementedusing a non-transitory computer readable medium having stored thereoncomputer executable instructions that when executed by the processor ofa computer control the computer to perform steps. Exemplary computerreadable media suitable for implementing the subject matter describedherein include non-transitory devices, such as disk memory devices, chipmemory devices, programmable logic devices, such as field programmablegate arrays, and application specific integrated circuits. In addition,a computer readable medium that implements the subject matter describedherein may be located on a single device or computing platform or may bedistributed across multiple devices or computing platforms.

As used herein, the term “node” refers to a physical computing platformincluding one or more processors and memory.

As used herein, the terms “function” or “module” refer to software incombination with hardware and/or firmware for implementing featuresdescribed herein. In some embodiments, a module may include afield-programmable gateway array (FPGA), an application-specificintegrated circuit (ASIC), or a processor.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter described herein will now be explained with referenceto the accompanying drawings of which:

FIG. 1 is a diagram illustrating an exemplary conventional LTE network;

FIG. 2 is a diagram illustrating an LTE node simulator according to anembodiment of the subject matter described herein; and

FIG. 3 is a diagram illustrating an exemplary process for initiatingeGTP indirect tunneling according to an embodiment of the subject matterdescribed herein.

DETAILED DESCRIPTION

The subject matter described herein discloses methods, systems, andcomputer readable media for initiating eGTP indirect tunneling. Whentesting LTE networks and/or other wireless communications network, itmay be desirable to test the response of the network and other equipmentunder non-trivial load conditions. During simulation and/or testing ofone or more LTE nodes, certain packet processing may be offloaded orperformed by a dedicated module (e.g., a FPGA or an ASIC). The dedicatedmodule may be configured to perform data processing operations morequickly than a general purpose module. In some instances, configuring adedicated module to handle numerous processing paths for various events(e.g., handover or other mobility events) may create excessivecomplexity and may require vast amounts of effort and other resources toimplement.

Advantageously, aspects of the present subject matter herein is directedto an LTE node simulator configured to identify packets as associatedwith endpoints no longer serving corresponding user devices and tobypass or avoid substantial processing of the packets by the dedicatedmodule. After identification, the packets may be routed or sent to acore network node so that the packets may be delivered to appropriatenodes, e.g., endpoints that are currently serving the corresponding userdevices associated with the data packets. In some embodiments, the LTEnode simulator may generate, maintain, and/or use a dynamic list ofidentifiers for identifying packets that need to be sent back to thecore network.

FIG. 1 diagram illustrating an exemplary conventional LTE network 100.In some embodiments, LTE network 100 may include one or more nodes of asystem architecture evolution (SAE) core or evolved packet core (EPC)network and/or other nodes. Referring to FIG. 1, LTE Network 100 mayinclude a LTE user device 102, a source eNB 104, a target eNB 106, asource serving gateway (SGW) 108, a target SGW 110, a packet gateway(PGW) 112 and a packet network 114 (e.g., the Internet). LTE user deviceor user equipment (UE) 102 may be any suitable device usable by a user(e.g., a mobile subscriber) to communicate via LTE network 100. Forexample, UE 102 may be a mobile phone, a laptop, a computing platform,or other device for communicating via LTE network 100.

ENBs 104 and 106 may each represent any suitable entity (e.g., a basetransceiver station (BTS), node B, etc.) for providing data via an airinterface. For example, eNB 104 may be an LTE mobile network entityhaving functionality similar to that of a radio network controller (RNC)and a base station (BS) in 2G networks or an RNC and a Node B in 3Gmobile networks. In some embodiments, eNBs 104 and 106 may communicatedirectly with LTE user devices and may be responsible for headercompression, ciphering, reliable delivery of packets, admission control,and radio resource management. ENBs 104 and 106 may also communicatewith various other modules and/or nodes, e.g., SGW 108, SGW 110, or amobility management entity (MME) for performing various control planesignaling functions such as network attaching, UE authentication, bearerchannel setup, and mobility management. In some embodiments, eNBs 104and 106 may be directly connected via X2 interfaces.

SGWs 108 and 110 may each represent any suitable entity (e.g., a nodecontaining a processor and a memory) for routing and forwarding datapackets. For example, SGW 108 (and PGW 112) may include functionssimilar to and/or functions different from a gateway GPRS support node(GGSN) in a 3G network. SGWs 108 and 110 may be nodes for providing datapaths between eNBs and PGW 112. For example, SGWs 108 and eNB 104 maycommunicate via an S1-U or other interface and SGWs 108 and PGW 112 maycommunicate via an S5 or S8 interface. In some embodiments, SGWs 108 and110 may part of an EPC or system architecture evolution (SAE) networkand packets may transverse SGW 108 using an eGTP or GTP protocol. SGWs108 and 110 may perform replication or notification procedures forlawful interception purposes. SGWs 108 and 110 may also act as amobility anchor for the user or data plane (e.g., during inter-eNBhandovers). SGWs 108 and 110 may manage and store UE contexts, e.g.,information associated with the IP bearer service. For example, for anidle state UE, SGW 108 may terminate a downlink data path and initiatepaging when downlink data arrives for the UE. SGWs 108 and 110 may alsobe used for communicating with other mobile networks, such as 2G/3Gnetworks. SGWs 108 and 110 may provide charging services and/or policyenforcement for UE 102, network 114, and service classes.

PGW 112 may represent any suitable entity for communicating withexternal packet data networks, such as packet network 114. For example,PGW 112 may be an access point for traffic to UE 102 from network 114.PGW 112 may perform policy enforcement, packet filtering, chargingsupport, lawful interception, and/or other functions. PGW 112 may alsoact as a mobility anchor between 3GPP and non-3GPP networks, such asCDMA and WiMAX networks. In some embodiments, UE 102 may havesimultaneous connectivity with multiple PGWs for accessing multiplepacket networks.

Packet network 114 may represent various nodes that communicate with UE102 via PGW 112. For example, packet network 114 may represent theInternet, or a portion thereof, and may include nodes external to an EPCnetwork (e.g., SGWs 108 and 110, PGW 112, an MME, and an HSS). Packetnetwork 114 may include web servers, media servers, and other nodes forproviding services and/or media content.

In some embodiments, UE 102 and packet network 114 may communicate datapackets via one or more tunneling protocols. For example, a GTP protocolor an eGTP protocol (e.g., eGTP-U) may be used to provide tunnelingsupport for communicating user data between eNB 106 and EPC elements(e.g., SGW 110 and PGW 112). UE context information, such as tunnelendpoint identifiers (TEIDs), medium access control (MAC) and/or IPaddresses, may be stored in the data packets and tunnels may be set upbetween various nodes. In some embodiments, a GTP protocol or an eGTPprotocol may be used for various interfaces, such as S1-U, S4, S5 and S8interfaces. GTP tunnels may be used to carry encapsulated transportpacket data units (T-PDUs) and signaling messages between tunnelendpoints. The transport bearer may be identified by a source TEID, adestination TEID, a source IP address, and/or destination IP address.

During inter-eNB handovers, incoming traffic at eNB 104 may be routedback to the core network (e.g., SGW 108) when UE moves to eNB 106 if nodirect connection (e.g., an X2 interface) exists between eNB 104 and106. For example, packet headers may be modified (e.g., a source MACaddress parameter value and target MAC address parameter value may beexchanged) before tunneling the modified packets toward eNB 106. In thisexample, the packets may be transported from eNB 104 to SGW 108, fromSGW 108 to SGW 110, and from SGW 110 to eNB 106. By sending the packetsback to a mobility anchor in the core network, the core network mayreroute the packets to UE 102 via eNB 106 thereby ensuring packets arenot lost during mobility events.

FIG. 2 is a diagram illustrating an LTE node simulator 200 according toan embodiment of the subject matter described herein. LTE node simulator200 may include a mobile network equipment simulation and/or testingplatform for simulating and testing one or more aspects of acommunications network and/or nodes therein. In some embodiments, LTEnode simulator may include various modules (e.g., circuits and/orsoftware executed by a processor) for connecting to various interfacesassociated with one or more mobile network equipment or nodes. Forexample, LTE node simulator 200 may be configured to simulate eNBs, UEs,and/or an MME for testing various aspects of an EPC network, or portionstherein (e.g., SGW 108).

Referring to FIG. 2, LTE node simulator 200 may include a processingmodule 202 and an eGTP module 204. Processing module 202 may be anysuitable entity for receiving, generating, and/or analyzing datapackets, such as real time protocol (RTP) packets. Processing module 202may include one or more communications interfaces. Each communicationsinterface may communicate with one or more interfaces, e.g., via GTP oreGTP tunnels. For example, an S1 interface, an S11 interface, an X2interface, and other interfaces associated with LTE node simulator 200or processing module 202 may be used for receiving or sending variousmessages.

In some embodiments, processing module 202 may include a processorand/or a circuit, such as an FPGA or ASIC, configured to receive,process, and/or generate data packets. Data packets may be encapsulatedwithin various headers and/or associated with protocols. For example,data packet may include RTP packets, user datagram protocol (UDP)packets, or transmission control protocol (TCP) packets. In someembodiments, data packets may include an eGTP header. The eGTP headermay include a destination TEID, a source TEID, or other identifiers,such as MAC addresses or IP addresses.

EGTP module 204 may be any suitable entity (e.g., software or logicexecuting on a processor) for generating and/or simulating data packetsand/or signaling or control plane packets. For example, eGTP module 204may generate various data packets and set up eGTP tunnels forcommunicating the data packets between UEs and packet network 114 viaEPC nodes in network 100. EGTP module 204 may include functionality formanaging simulation of various nodes (e.g., eNBs, MMEs, UEs, and/orother adjacent or related nodes). For example, eGTP module 204 may helpperform multi-UE simulation, eNB simulation, UE call dispatching(including both real and simulated UEs), UE traffic profileconfiguration, call automation, quality of service (QoS) testing,selective reporting and statistics, and call tracing.

In some embodiments, eGTP module 204 may execute user scripts forperforming various actions or simulations. For example, user scripts mayinclude or indicate various simulation scenarios, such as predeterminedsequences of messages representing simulated actions performed bysimulated UEs. In some embodiments, user scripts may include one or morepre-defined scripts for simulating different LTE traffic/load scenariosin which multiple UEs are connected to an eNB. At any given time, theload on a simulated eNB may include UEs continuously connecting anddisconnecting to the network, making and receiving calls, sending data,roaming to another eNB within the network, etc. Moreover, the particularmix of UEs and how they behave may be highly dependent upon the networkcarrier and/or the device under test's location within the network.Therefore, user scripts may include a wide variety of primitive/basicoperations that are typically performed by individual UEs so that anetwork operator can customize their simulated traffic mix to be similarto real world scenarios of interest.

For example, user scripts may include originating scripts associatedwith a simulated UE that originates a call/session. Originating scriptsmay include, but are not limited to, attach, detach, sessionestablishment and release, handover, session initiation protocol (SIP)calls, file transfer protocol (FTP) calls, and hypertext transferprotocol (HTTP) calls. Conversely, user scripts may also includeterminating scripts associated with a simulated UE that terminates acall/session such as MME-initiated detach, HSS-initiated detach,handover, and SIP/FTP/HTTP calls.

EGTP module 204 may generate and/or maintain a data structure orindirect tunnel TEID list 206 for storing various identifiers associatedwith one or more events. For example, eGTP module 204 may identify theUEs for which indirect tunnels need to be created based on mobilityevents (e.g., attach, handover, and/or detach events) and may storeTEIDs or other identifiers associated with the UEs in TEID list 206.TEID list 206 may include any suitable entity (e.g., a non-transitorycomputer readable medium) useable for storing information foridentifying UEs or bearer connections involved in active voice calls atthe time of a mobility event (e.g., a handover procedure). In someembodiments, entries may be dynamically added based on one or morefactors, such as simulation scenarios including mobility events andactive calls.

As stated above, LTE node simulator 200 and/or processing module 202 canimprove efficiency and resource utilization by reflecting or re-routingcertain data packets back to SGW 108 or another network node. Forexample, after receiving a data request from UE 102, traffic from an IMSnetwork or packet network 114 may be routed through PGW 112 and SGW 108towards UE 102. When a mobility event occurs, such as UE 102 detachingfrom a first transceiver simulated by LTE node simulator 200 and movingto a second transceiver, the traffic that is already en route may beidentified and routed back to the core network without being fullyprocessed by processing module 202.

In some embodiments, processing module 202 may include an FPGAconfigured to generate and/or analyze stateful or session-aware RTPtraffic. Before fully processing a data packet, processing module 202may receive, obtain, or access a TEID contained in the data packet.Processing module 202 may also request, receive, or otherwise accessTEID list 206, e.g., from eGTP module 204. Processing module 202 maycheck, query, or otherwise use the obtained identifier and TEID list 206to determine whether a data packet should be processed or whether thedata packet should be reflected (e.g., sent back to a network node fordelivery to another transceiver).

In some embodiments, if the identifier associated with the data packetmatches an entry in TEID list 206, processing module 202 may stopprocessing the data packet and may forward or send the data packet toeGTP module 204 and/or an egress port. For example, an RTP packet may besent to a port and/or an associated processor configured to send thedata packet to SGW 108 or another network node. The “reflected” datapacket may be sent via one or more indirect tunnels and may beeventually received by UE 102 via a second transceiver.

In some embodiments, LTE node simulator, or a module therein, may modifyone or more portions of the data packet. The modification may be forrouting the data packet to a network node and/or a subsequentdestination. For example, after determining that a data packet is to besent back to SGW 108, a destination MAC address parameter value and asource MAC address parameter value in the RTP header may be exchanged sothat the new destination MAC parameter value is the original source MACaddress parameter value and vice versa. In another example, other headerinformation may be added, deleted, and/or modified.

In some embodiments, the second transceiver may include a simulatedtransceiver. For example, after receiving a reflected data packet, anetwork node may route the data packet toward an eNB that is simulatedby LTE node simulator 200 or another entity. In this example, processingmodule 202 may obtain a TEID associated with the data packet, determinethat TEID does not match an entry in TEID list 206 (e.g., the TEID indata packet is associated with the second transceiver), and may processand/or analyze the packet.

In some embodiments, the second transceiver may include an eNB, a nodeB, a base station or other node that is separate from LTE node simulator200. For example, after receiving a reflected data packet, a networknode may route the data packet toward eNB 106. In this example, eNB 106may process the packet.

FIG. 3 is a diagram illustrating an exemplary process for initiatingeGTP indirect tunneling according to an embodiment of the subject matterdescribed herein. In some embodiments, the exemplary process describedherein, or portions thereof, may be performed by LTE node simulator 200,processing module 202, eGTP module 204, and/or another node or module.

In step 300, an eGTP encapsulated data packet associated with a userdevice may be received from a device under test. The data packet mayinclude an endpoint identifier for identifying a first transceiversimulated by the LTE node simulator. For example, a data packet may bereceived via an eGTP tunnel between SGW 108 and LTE node simulator 200.The packet may include a TEID that indicates an eNB simulated by LTEnode simulator 200.

In some embodiments, the data packet may include an RTP packet, a UDPpacket, or a TCP packet. In some embodiments, the data packet may bereceived by or at a communications interface associated with LTE nodesimulator 200 or a processing module. In some embodiments, theprocessing module may include a FPGA, an ASIC, or a processor.

In step 302, it may be determined, using the endpoint identifier,whether the data packet is associated with a real or simulated userdevice that is no longer attached to the first transceiver. For example,before fully processing a data packet, processing module 202 may parsean eGTP header of the data packet and obtain a TEID (e.g., a destinationTEID). Using the TEID and a dynamic TEID list 206 provided by eGTPmodule 204, processing module 202 may identify a packet as no longerbeing attached to the first transceiver or being associated with adifferent transceiver, e.g., a mobility event or handover procedureoccurs thereby associating the user device with target eNB 106.

In some embodiments, determining that the data packet should not beprocessed by the module may include querying, using the endpointidentifier, a data structure containing endpoint identifiers that areassociated with user devices that recently performed mobility events(e.g., an inter-eNB handover procedure) and receiving an indication thatthe endpoint identifier matches an entry in the data structure. In someembodiments, the data structure may dynamically add a user device thatis involved in a call when the mobility event occurs (e.g., when ahandover is initiated, in progress, or is completed).

In step 304, in response to determining that the data packet isassociated with a real or simulated user device that is no longerattached to the first transceiver, at least a portion of the data packetto the device under test may be sent using an eGTP tunnel. For example,before fully processing a data packet, processing module 202 may obtaina TEID from the data packet. Using the TEID and a dynamic TEID list 206provided by eGTP module 204, processing module 202 may identify a packetas being associated with a new transceiver and may bypass or stopfurther processing. Processing module 202 may send the data packet to anegress port for forwarding the data packet back to a core network node.

In some embodiments, sending at least a portion of the data packet tothe device under test using an eGTP tunnel may include modifying thedata packet, sending the modified data packet to the device under test,or routing the modified data packet to a second transceiver that isassociated with the user device. For example, modifying the data packetmay include inverting or exchanging identifiers (e.g., a source MACaddress becoming a destination MAC address and vice versa) in one ormore headers associated with the data packet.

In some embodiments, the device under test may include a simulatednetwork node, a core network node, a gateway, a mobility managemententity, or a server. For example, a network node may include a SGW, aPGW, and/or other nodes in an EPC network or an LTE network. In anotherexample, a network node may be simulated by another node or module,e.g., LTE node simulator 200 or other mobile network equipmentsimulation and/or testing platform.

It will be understood that various details of the subject matterdescribed herein may be changed without departing from the scope of thesubject matter described herein. Furthermore, the foregoing descriptionis for the purpose of illustration only, and not for the purpose oflimitation, as the subject matter described herein is defined by theclaims as set forth hereinafter.

What is claimed is:
 1. A method for initiating evolved general packetradio service (GPRS) tunneling protocol (eGTP) indirect tunneling, themethod comprising: at a long term evolution (LTE) node simulatorincluding a module for processing data packets: receiving, from a deviceunder test, an eGTP encapsulated data packet associated with a userdevice, the data packet including an eGTP header having an endpointidentifier for identifying a first transceiver simulated by the LTE nodesimulator; determining, using the endpoint identifier, whether the datapacket is associated with a real or simulated user device that is nolonger attached to the first transceiver, wherein determining that thedata packet is associated with a real or simulated user device that isno longer attached to the first transceiver includes querying, using theendpoint identifier, a data structure containing endpoint identifiersthat are associated with user devices that recently performed mobilityevents and receiving an indication that the endpoint identifier matchesan entry in the data structure; and in response to determining that thedata packet is associated with a real or simulated user device that isno longer attached to the first transceiver, sending at least a portionof the data packet to the device under test using an eGTP tunnel.
 2. Themethod of claim 1 where sending at least a portion of the data packet tothe device under test using an eGTP tunnel includes: modifying the datapacket; sending the modified data packet to the device under test; orrouting the modified data packet to a second transceiver that isassociated with the user device.
 3. The method of claim 1 comprising inresponse to determining that the data packet is associated with a realor simulated user device that is attached to the first transceiver,processing the data packet.
 4. The method of claim 1 wherein the userdevices are dynamically added to the data structure based on whether theuser devices are involved in active calls when the mobility eventsoccur.
 5. The method of claim 1 wherein the first transceiver includes abase station, a node b, or an evolved node b (eNB).
 6. The method ofclaim 1 wherein the device under test includes a simulated network node,a core network node, a gateway, a mobility management entity, or aserver.
 7. The method of claim 1 wherein the user device includes asimulated user device.
 8. The method of claim 1 wherein the LTE nodesimulator simulates multiple transceivers.
 9. The method of claim 1wherein the endpoint identifier includes a tunnel endpoint identifier(TEID).
 10. The method of claim 1 wherein the module includes afield-programmable gateway array (FPGA), an application-specificintegrated circuit (ASIC), or a processor.
 11. A system for initiatingevolved general packet radio service (GPRS) tunneling protocol (eGTP)indirect tunneling, the system comprising: a long term evolution (LTE)node simulator including a module for processing data packets, the LTEnode simulator comprising: the module configured to receive, from adevice under test, an eGTP encapsulated data packet including an eGTPheader having an endpoint identifier for identifying a first transceiversimulated by the LTE node simulator, to determine whether the datapacket is associated with the user device that is no longer attached tothe first transceiver, and in response to determining that the datapacket is associated with the user device that is no longer attached tothe first transceiver, to send at least a portion of the data packet tothe device under test using an eGTP tunnel, wherein the module isconfigured to determine that the data packet is associated with a realor simulated user device that is no longer attached to the firsttransceiver by querying, using the endpoint identifier, a data structurecontaining endpoint identifiers that are associated with user devicesthat recently performed mobility events and receiving an indication thatthe endpoint identifier matches an entry in the data structure.
 12. Thesystem of claim 11 where the module is configured to initiate routingthe data packet to the device under test using an eGTP tunnel by:modifying the data packet; sending the modified data packet to thedevice under test; or routing the modified data packet to a secondtransceiver that is associated with the user device.
 13. The system ofclaim 11 wherein the module is configured to process the data packet inresponse to determining that the packet is associated with a real orsimulated user device that is attached to the first transceiver.
 14. Thesystem of claim 11 comprising: an eGTP module configured to maintain thedata structure and to dynamically add an identifier to the datastructure based on whether a related user device is involved in anactive call when the mobility event occur.
 15. The system of claim 11wherein the first transceiver includes a base station, a node b, or anevolved node b (eNB).
 16. The system of claim 11 wherein the deviceunder test includes a simulated network node, a core network node, agateway, a mobility management entity, or a server.
 17. The system ofclaim wherein the user device includes a simulated user device.
 18. Thesystem of claim 11 wherein the LTE node simulator simulates multipletransceivers.
 19. The system of claim 11 wherein the endpoint identifierincludes a tunnel endpoint identifier (TEID).
 20. The system of claim 11wherein the module includes a field-programmable gateway array (FPGA),an application-specific integrated circuit (ASIC), or a processor.
 21. Anon-transitory computer readable medium comprising computer executableinstructions embodied in the non-transitory computer readable mediumthat when executed by a processor of a computer control the computer toperform steps comprising: at a long term evolution (LTE) node simulatorincluding a module for processing data packets: receiving, from a deviceunder test, an eGTP encapsulated data packet associated with a userdevice, the data packet including an eGTP header having an endpointidentifier for identifying a first transceiver simulated by the LTE nodesimulator; determining, using the endpoint identifier, whether the datapacket is associated with a real or simulated user device that is nolonger attached to the first transceiver, wherein determining that thedata packet is associated with a real or simulated user device that isno longer attached to the first transceiver includes querying, using theendpoint identifier, a data structure containing endpoint identifiersthat are associated with user devices that recently performed mobilityevents and receiving an indication that the endpoint identifier matchesan entry in the data structure; and in response to determining that thedata packet is associated with a real or simulated user device that isno longer attached to the first transceiver, sending at least a portionof the data packet to the device under test using an eGTP tunnel.